The booklet measures 12,5 x 8 cm (closed). It consists of accordion folded cardboard. Start with the first crease in the middle of the paper and make creases every 8 cm. I folded the edges 5 cm inwards on both sides (see first picture). I made a hole in the middle of the outside creases and in the one's beside and put a ribbon through them (see second picture).

Then I stuck the edges, except in the middle, the ribbon should still be able to move.